Many websites utilise CAPTCHA (Completely Automatic Public Turing tests to tell Computers and Humans Apart) schemes as human interaction proofs to grant access to their services only to people rather than spam bots. In this paper, we examine the security of six widely used types of CAPTCHA and present novel attacks against all of them, achieving success rates of up to 88%. We made improvements ...

Abstract In this paper, the CAPTCHA code is recognized based on character segmentation and random forest algorithm. recognition process, gray conversion method, binarization Gaussian filtering method are used to process image, then projection segment characters. Using algorithm recognize a single character, accuracy reaches 94%. recognition, it found that 5 S, 8 B, 4 A, T F have lowest resoluti...

CAPTCHAs are an important security tool for preventing automated attacks against online systems. However, they can be an undesirable source of friction in the user experience. In this poster, we propose a novel approach to dynamically improve the CAPTCHA experience for users by individually learning which types of CAPTCHA tests each user is best at solving and adapting future tests presented ba...

Web access is affected by a great amount of accessibility issues that do not allow some users to access all information presented. Therefore, Web accessibility is an important issue because everybody should access Web content independently of their access features. Among these accessibility issues, a Web content element that interferes with Web accessibility is a CAPTCHA. A CAPTCHA is a challen...

Facial/voice-based authentication is becoming increasingly popular (e.g., already adopted by MasterCard and AliPay), because it is easy to use. In particular, users can now authenticate themselves to online services by using their mobile phone to show themselves performing simple tasks like blinking or smiling in front of its built-in camera. Our study shows that many of the publicly available ...

22 COPublished by the ieee COmPuter and reliability sOCieties ■ 1540-7993/09/$26.00 © 2009 ieee ■ July/august 2009 Completely Automated Public Turing Tests to Tell Computers and Humans Apart (CAPTCHAs) are now an almost standard security mechanisms for defending against undesirable and malicious bot programs on the Internet (especially those bots that can sign up for thousands of accounts a min...

With the growing and prevalent usage of Internet, threat for the service providers has arisen. One of the most important aspects of modern security concerns is to deal with users that are computer programs or bots. These programs pretend to be human users and exploit servers by submitting data automatically, thereby, hindering the services of the server. Security mechanism dealing with such att...

The multimedia research community has, for long, attempted to recognize generic images, make them searchable by content, annotate them, and associate them with linguistic indexes. In the course of these attempts, the limitations of state-of-the-art algorithms in mimicking human vision has become wellknown. In this paper, we explore the exploitation of this limitation for solving a security prob...

Visual cryptography (VC) technique encodes an image into two or more shares that appear random in human eyes. In the decryption section, pixels shared images are combined to obtain information contained original image. This study applies visual cryptographic techniques graysle and color for user authentication online transactions using VC2,2 scheme. The server computer CAPTCHA sent through diff...